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Modelling Ancient Earth Climate: Modelling Ancient Earth Climate: Methods & ModelsMethods & Models
Prof. Alan M. HaywoodProf. Alan M. Haywood
School of Earth & Environment, University of Leeds, Leeds, School of Earth & Environment, University of Leeds, Leeds, LS2 9JT.LS2 9JT.
with contributions from Paul Valdes, Ulrich Salzmann, with contributions from Paul Valdes, Ulrich Salzmann, Victoria Peck, Steve Hunter & Jane FrancisVictoria Peck, Steve Hunter & Jane Francis
Why?Why?
• Understand the dynamics of warm Understand the dynamics of warm climatesclimates
• Test Earth System ModelsTest Earth System Models
• Simulation of the historical or near-historical recordSimulation of the historical or near-historical record
• Analysis of the observed record of variabilityAnalysis of the observed record of variability
• Projection for the next 100 years Projection for the next 100 years
Primary Research Focus in Climate Primary Research Focus in Climate Change ScienceChange Science
Greatest StrengthsGreatest Strengths
Spatial and temporal character of the Observations.Spatial and temporal character of the Observations.
Measurement of physical quantities that define the Measurement of physical quantities that define the state of the atmosphere and ocean.state of the atmosphere and ocean.
Greatest WeaknessesGreatest Weaknesses
Sense of change.Sense of change.
Sense of the integration of the Earth System.Sense of the integration of the Earth System.
Greatest StrengthsGreatest Strengths
Spectacular sense of change (Spectacular sense of change (Furry Alligator Furry Alligator SyndromeSyndrome))
True integrated system responseTrue integrated system response
Greatest WeaknessesGreatest Weaknesses
Proxies rather than state variablesProxies rather than state variables
Limited spatial and temporal resolutionLimited spatial and temporal resolution
In contrast: A In contrast: A Research Focus in Research Focus in
Earth HistoryEarth History
““The greatest weaknesses in a The greatest weaknesses in a research focus on the modern record research focus on the modern record are the greatest strengths of Earth are the greatest strengths of Earth
System History”System History”
We Should Worry
IPCC Climate Sensitivity: IPCC Climate Sensitivity: Roughly 1.5 to 4.5 C globally averaged surface temperature increase for a doubling of
carbon dioxide.
Hundreds of GCM experiments have been completed for Hundreds of GCM experiments have been completed for time periods throughout the Phanerozic using a wide time periods throughout the Phanerozic using a wide variety of climate models.variety of climate models.
Many experiments focused on either glacial climates or Many experiments focused on either glacial climates or warm climates (the extremes).warm climates (the extremes).
““There is no legitimate example of a climate model There is no legitimate example of a climate model simulationsimulation
in which the past climate conditions were in which the past climate conditions were overestimated”overestimated”
ClimateClimateHistoryHistory
Atmospheric carbon dioxide through the Phanerozoic and projected into
the next century. Inset modified from figure constructed by S. Porter (2003). L. Sohl constructed the Phanerozoic portion
(2003).
The Climate System
General Circulation General Circulation ModelsModels
Model needs to simulate albedo, emissivity and general circulation.
Use “first principles”
Newton's Laws of Motion
1st Law of Thermodynamics
Conservation of Mass and Moisture
Hydrostatic Balance
Ideal Gas Law
Spectrum of Climate ModelsSpectrum of Climate Models
Energy Balance Models (EBM’s)Energy Balance Models (EBM’s)
Atmospheric General Circulation Models (AGCM)Atmospheric General Circulation Models (AGCM)
AGCM + Slab Ocean ModelAGCM + Slab Ocean Model
Coupled Ocean Atmosphere GCM Coupled Ocean Atmosphere GCM (OAGCM)(OAGCM)
EMICEMIC
ESMESM
Number
Com
ple
xit
y
Components of an Components of an Earth System ModelEarth System Model
Aerosols:Aerosols:
Dust and SulphatesDust and Sulphates
Aerosols:Aerosols:
Dust and SulphatesDust and SulphatesRegional Model:Regional Model:High ResolutionHigh ResolutionRegional Model:Regional Model:High ResolutionHigh Resolution
Cryosphere-Cryosphere-LithosphereLithosphere
ModelModel
Cryosphere-Cryosphere-LithosphereLithosphere
ModelModel
AtmosphericAtmosphericChemistryChemistry
AtmosphericAtmosphericChemistryChemistry
Atmospheric General Atmospheric General Circulation ModelCirculation Model
Atmospheric General Atmospheric General Circulation ModelCirculation Model
Land SurfaceLand SurfaceHydrologyHydrology
Land SurfaceLand SurfaceHydrologyHydrology
Ocean General Ocean General Circulation ModelCirculation Model
Ocean General Ocean General Circulation ModelCirculation Model
Ocean Carbon CycleOcean Carbon Cycle
Ocean Carbon CycleOcean Carbon Cycle
Terrestrial CarbonTerrestrial CarbonCycleCycle
Terrestrial CarbonTerrestrial CarbonCycleCycle
Brief history of numerical modelling
ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN ICEICE SULPHURSULPHUR CARBON CARBON CHEMISTRYCHEMISTRY
ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN ICEICE SULPHURSULPHUR CARBON CARBON
ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN ICEICE SULPHURSULPHUR
ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN ICEICE
ATMOSPHEREATMOSPHERE LANDLAND OCEANOCEAN
ATMOSPHEREATMOSPHERE LANDLAND
ATMOSPHEREATMOSPHERE
19991999
19971997
19921992
19851985
Development of Met. Office Climate Models
Component models
are constructed off-line
and coupled in to the
climate model when
sufficiently developed1960s1960s
PresentPresent
19901990
Physical basis of climate models
• The atmosphere is a fluid on a rotating planet:– Drag at the surface and within the atmosphere affects the
momentum budget– Water vapour evaporates from the surface, condenses to
form clouds and heats the atmosphere when it is lost through precipitation
– Heating from solar radiation and cooling from thermal radiation
• Models therefore need to include equations for;– 3 components of wind (or vorticity & divergence), including
Coriolis and drag– equation of state and conservation of water– thermodynamics, including heating by condensation and
radiation
• The ocean is also a fluid, but incompressible. It is The ocean is also a fluid, but incompressible. It is heated by solar radiation and cooled by heated by solar radiation and cooled by evaporation and thermal emission from the evaporation and thermal emission from the surface. No internal heating, but salinity strongly surface. No internal heating, but salinity strongly affects the density and hence the circulationaffects the density and hence the circulation
• Additional models have been developed to Additional models have been developed to include the land surface, cryosphere, atmospheric include the land surface, cryosphere, atmospheric chemistry and aerosols, carbon cycle etcchemistry and aerosols, carbon cycle etc
• Processes that are sub-grid in scale are Processes that are sub-grid in scale are modelled by modelled by parametrizationsparametrizations
Physical basis of climate Physical basis of climate modelsmodels
HadCM3 GCM
20 Ocean Levels
19 Atmospheric Levels
Atmospheric resolution: 3.75 by 2.5 degrees
Ocean resolution :1.25 by 1.25
19 levels in atmosphere
20 levelsin ocean
2.5lat 3.75
long
1.251.25
THE HADLEYCENTRETHIRDCOUPLEDMODEL -HadCM3no flux adjustments
30km
-5km
Parametrized processes in the ECMWF model
Representation of orography;
the importance of resolution
The upper figure shows the surface orography over North America at a resolution of 480km, as in a low resolution climate model.
The lower figure shows the same field at a resolution of 60km, as in a weather forecasting model.
Remember that orographic processes are highly non-linear.
The horizontal and vertical resolutions of climate models need to be high enough to avoid numerical errors and to resolve the basic dynamical and transport processes
There is a trade-off between resolution and computing time, but model resolutions are increasing continually, as more computer power becomes available
So………So………
Ice Sheet Ice Sheet ElevationElevation
From Peltier, 1994
Temperature Temperature ChangeChange
BiomesBiomesPrecipitationPrecipitation
Case Case StudiesStudies
1. Palaeo ENSO (El Ni1. Palaeo ENSO (El Niñño Southern Oscillation)o Southern Oscillation)
• Coupled ocean-atmosphere phenomena
• Involves large scale fluctuations in a number of oceanic/atmospheric variables (e.g. sea surface temps. & sea level pressure)
• El Niño & La Niña opposite extremes of ENSO
The Pliocene: a Permanent El NiThe Pliocene: a Permanent El Niñño-like state?o-like state?(Wara et al., 2005; Philander & Federov, 2003)(Wara et al., 2005; Philander & Federov, 2003)
Mg/Ca SSTsMg/Ca SSTs
00 55Age (Ma)Age (Ma)
33
Strong GradientStrong Gradient No GradientNo Gradient
Difference between PlioceneDifference between PlioceneControlControl and Pre-Ind (and Pre-Ind (C) C)
00
400400
10001000
30003000
50005000
-2 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38
Plio c e ne c o ntro l o c e a n tem p e ra tures ( a c ro ss the Pa c ific a t 0°C ) °NPlioPlioControlControl ocean temperatures ( ocean temperatures (C) C)
across the Pacific at 0across the Pacific at 0NN
Can a model reproduce this change?Can a model reproduce this change?
ENSO rather than permanent El-NiENSO rather than permanent El-Niñño!o!
Haywood et al. (in-press). Paleoceanography
“In search of palaeo-ENSO: significance of changes in the
mean state”
1 sample per 10,000 years
Mid Holocene ENSO Mid Holocene ENSO - Palaeo Data- Palaeo Data
G. bulloidesUpwelling
G. rubersummer
ENSO - Interannual variability
Single specimen analyses however, may provide insight to the range of seasonal extremes within time slices, similar to modern studies in the Gulf of California.
McConnell & Thunell, 2005
El Nino
La Ninaxxx
xx
x
xxx
xx
x
xxx
DJF Surface Air Temperature (°C) El-Niño Region 3.4
20
2122
23
24
2526
27
28
2930
31
32
0 10 20 30 40 50 60 70 80 90 100
Integration length (Years)
Su
rfa
ce
Air
Te
mp
era
ture
(°
C)
du
rin
g D
JF
Pre-Industrial
PlioControl
PlioCAS
Standard Deviations:Pre-Ind = 0.69
PlioControl = 0.89
PlioCAS = 0.57
Additional Modelling ExperimentsAdditional Modelling Experiments
• Ocean GatewaysOcean Gateways• Trace Gas ConcentrationsTrace Gas Concentrations• Altered Model ParametersAltered Model Parameters
Case Case StudiesStudies
2. Ice-Sheet Initiation (E/O boundary)2. Ice-Sheet Initiation (E/O boundary)
E/O E/O boundaryboundary
Marine Marine 181800
Antarctic ice-Antarctic ice-rafted detritusrafted detritus
PalaeobotanicPalaeobotanical al
EvidenceEvidenceZachos et al. (2001)
Palaeocene Present
Antarctica: from Greenhouse to Ice-houseAntarctica: from Greenhouse to Ice-house
Causal Mechanisms for Antarctic Causal Mechanisms for Antarctic Ice-Sheet InitiationIce-Sheet Initiation
• • Ocean GatewaysOcean Gateways
• • Antarctic elevationAntarctic elevation
• • Declining atmospheric Declining atmospheric COCO22 concentrations concentrations
Important Gateways
Evolution of major ocean gateways since the Eocene. During the last 50 million years (Ma) subtropical gateways (blue bars) closed and high latitude gateways (red bars) opened. (Figure courtesy of Bill Hay, GEOMAR).
GCM - ClimatologiesGCM - ClimatologiesDeConto & Pollard, 2003.DeConto & Pollard, 2003.
DeConto & Pollard, 2003.DeConto & Pollard, 2003.
Ice-sheet ModelIce-sheet Model
DeConto & Pollard, 2003.DeConto & Pollard, 2003.
2 X CO2
3 X CO2
Ice-sheet ModelIce-sheet Model
DeConto & Pollard, 2003.DeConto & Pollard, 2003.
Sensitivity TestsSensitivity Tests
Initial Initial ModellingModelling
Case Case StudiesStudies
3. Cretaceous Climates & Ice-Sheets3. Cretaceous Climates & Ice-Sheets
PalaeobotanicPalaeobotanical al
EvidenceEvidenceCretaceous forest 120 Cretaceous forest 120 million years ago on the million years ago on the Antarctic Peninsula. Antarctic Peninsula. reconstruction based reconstruction based on PhD of Jodie Howe, on PhD of Jodie Howe, University of Leeds/BAS, University of Leeds/BAS, painted by Robert Nichols.painted by Robert Nichols.
Evidence for large, rapid sea-level changes (Miller et al., 2005)
• Evidence for eustatic nature
• Pace and magnitude suggest glacial origin.
• Suggest moderate-sized ice sheets (5 - 10 × 106 km3 ).
• Paced by Milankovitch forcing.
CO2 levels through the Maastrichtian
• 2 greenhouse episodes 1000-1400 ppm
• But suggestions of CO2 low-points at ~70 and 66 Ma.
(Nordt et al., 2003; Beerling et al., 2002).
How to create a How to create a Maastrictian modelMaastrictian model
Change solar output ~0.6% less than present
CO2 (and other gases) 4 x pre-industrial (but could be 2x to 8x.
Volcanic activity Assume same as today.
Change in orbit Same as present, but performsensitivity simulations
Palaeogeography Including sea-level/ orography/ bathymetry/land ice
Previous modelling also required prescription of vegetation, and sea surface temperatures (or ocean heat transport) but this is no longer needed.
Maastrictian OrographyMaastrictian Orography
At climate model resolution. Original palaeogeographies from Paul Markwick
Coupled Ocean-Atmosphere Coupled Ocean-Atmosphere Simulation:Simulation:
Comparison to Oxygen IsotopesComparison to Oxygen Isotopes
Paul Pearson's Maastrictian data
Model predicted temperatures approx. 10C at 1000m, 8C at 2000m, and 7C at 3000m
c.f. temperatures from 14C to 7C from D’Hondt & Arthur (2002)
Coupled Ocean-Atmosphere Coupled Ocean-Atmosphere Simulation:Simulation:
Comparison to Vertebrate DataComparison to Vertebrate Data
Paul Markwick's database
Red squares= all crocs, Orange= Dinosaurs, White = Other Vertebrates
Model predicted cold month mean shown by 5C contour (red) and 0C (blue)
2xCO2 - ~ 2 x 106 km3 ice
• Suite of HadCM3 derived palaeoclimatesSuite of HadCM3 derived palaeoclimates– 2, 4, and 6 x CO2, 4, and 6 x CO2 2
– Further runs being carried out including 1 x Further runs being carried out including 1 x COCO22
• Comparison against climate proxy Comparison against climate proxy databasedatabase
• Climate then used to drive a BAS ice-Climate then used to drive a BAS ice-sheet model.sheet model.
2xCO2
4xCO2 + favourable orbit
Ice Sheets in a Greenhouse WorldIce Sheets in a Greenhouse World
The Future: Data & Models The Future: Data & Models CombineCombineLimiting Factors:
• Available computer power• Model sophistication (resolution etc.)• Small community (“every department needs a pet modeller”)• Language barriers & a lack of communication• A new generation of scientists to act as the interface
A couple of examples what modellers need from the geological community
• Ocean temperatures• Land cover
“Deep-time perspectives on climate change: marrying the signal from computer models and biological proxies (Eds. M. Williams, A. M. Haywood, J. Gregory and D. Schmidt) The Micropalaeontological Society & the Geological Society of London”
Oceans:Quantitative temperature estimates derived from multi-proxy studiesPRISM & MARGO
H. Dowsett (in-press).
Kucera et al. (2005) QSR Vol. 24, 813-819
New 3-D Ocean Temperature New 3-D Ocean Temperature Reconstructions: multiple equilibrium?Reconstructions: multiple equilibrium?
M e r id io n a l O v e r tu r in g Stre a m fu n c t io n (S v ) G lo b a l P lio - P re se n t
Land Cover:Land Cover:Vegetation and Biomes derived from paleobotanical studies
Proxies BiomesData
Dates (BP) Depth (cm.)
Lith
olo
g
y
Rain
fo
rest
less fern
s
MS
F.-
Rh
izo
ph
ora
Micro
fao
ra.test
Po
aceae
Elaeis
gu
in
een
si
s
Fu
ng
al
sp
ores
10 22.8 12 31.7
3109 30 33.7 7 5.3
40 48 1.8 38.5 4.4
60 Reddish black-dark reddish grey
21.8 67.9 2.4
70 35 47.9 3.1 6.7
110 16.7 89 0.8
130 36 96.1 0.3
140 13.8 75.2 0.7 0.3
5682 150 Black-dark reddish brown
2.7 45.5
185 28 95.4 0.4 0.2
210 17.2 95.7 0.2 0.4 0.4 0.6
240 21.3 97 0.2 0.2
300 94 0.4 0.4
340 20 97.3 0.3 2.4
6409 400 19.8 95.6 0.1 0.5 12.8
410 10 96.7 1
450 32.7 99.3 1.4
500 93.2 0.3 0.3
510 + 0.1
6681 520 +
530 +
540 +
550 +
560 9.1 96.7 0.3 0.3
580 15 93.3 0.3 0.3
600 6.3 97.4
660 13.9 93.4
670 ++
Black-dark grey
Black
Black
Dark reddish brown
Very dark grey-black
Translation and Reconstruction
Nearest Living Relatives
Plant functional types
Full Biomisation
Fossil Leaves
Pollen
Fossil Wood
Rainforest
Grassland
Savanna
PLIOCENE BIOMES:PLIOCENE BIOMES:DATA–MODEL COMPARISONDATA–MODEL COMPARISON
Paleo-Data Biomes
Model Biomes
SummarySummary
• Glaciation in a Greenhouse word? Glaciation in a Greenhouse word?
• Importance of ACC on EAIS kick off?Importance of ACC on EAIS kick off?
• Permanent El-Niño?Permanent El-Niño?
• How its DoneHow its Done
• Need for Integration Need for Integration
• Why Model?Why Model?
NO PROBLEMNO PROBLEM